The following references may be relevant to the general field of technology of the present disclosure: U.S. Pat. Nos. 8,096,508; 5,959,775; 4,948,859; 4,859,742; 4,302,553; 8,916,271; 6,623,824; 7,713,604; 8,668,166; US 2010/0282909; and US 2014/0174642.
U.S. Pat. No. 8,916,271 relates to semi-IPN polyurethane/polyurea protective films.
U.S. Pat. No. 6,623,824, “Method for Making a Microreplicated Article Using a Substrate Comprising a Syndiotactic Vinyl Aromatic Polymer,” purports to describe a “urethane acrylate IPN formulation,” e.g., at Examples 14, 15, C1, 20, and 21. The term “IPN” is used there in a manner inconsistent with the manner in which it is used in the present application. Each “urethane acrylate IPN formulation” of U.S. Pat. No. 6,623,824, Examples 14, 15, C1, 20, and 21 includes caprolactone acrylate, a monomer having a hydroxy group reactive with polyurethane-forming (polyisocyanate) monomers at one end, and an acrylate group reactive with polyacrylate-forming monomers at the other. Therefore, it is believed that upon heat cure of the polyurethane-forming and polyacrylate-forming monomers of the “urethane acrylate IPN formulation,” one single polymer network is formed.